<template>
  <div class="s-canvas">
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight" />
  </div>
</template>
<script>
export default {
    name: 'VerificationCode',
    props: [
        'identifyCode', // string
        // 'fontSizeMin',
        // 'fontSizeMax',
        // 'backgroundColorMin',
        // 'backgroundColorMax',
        // 'colorMin',
        // 'colorMax',
        // 'lineColorMin',
        // 'lineColorMax',
        // 'dotColorMin',
        // 'dotColorMax',
        'contentWidth', // width  number
        'contentHeight' // height number
    ],
    data() {
        return {
            // identifyCode: "1234",
            fontSizeMin: 20,
            fontSizeMax: 36,
            backgroundColorMin: 248,
            backgroundColorMax: 248,
            colorMin: 50,
            colorMax: 50,
            lineColorMin: 40,
            lineColorMax: 40,
            dotColorMin: 50,
            dotColorMax: 50,
            fixedBgColor: 'rgba(12, 60, 106,1 )',
            fixedFontColr: 'rgba(203,233,255,1)',
            isDrawLine: true,
            isDrawDot: true,
            fixedFontSize: 0,
            fixedLineColor: 'rgba(203,233,255,0.6)',
            fixedDotColor: 'rgba(203,233,255,0.6)'

            // contentWidth: 112,
            // contentHeight: 38
        }
    },
    watch: {
        identifyCode() {
            this.drawPic()
        }
    },
    mounted() {
        this.drawPic()
    },
    methods: {
        // 生成一个随机数
        randomNum(min, max) {
            return Math.floor(Math.random() * (max - min) + min)
        },
        // 生成一个随机的颜色
        randomColor(min, max) {
            const r = this.randomNum(min, max)
            const g = this.randomNum(min, max)
            const b = this.randomNum(min, max)
            return 'rgb(' + r + ',' + g + ',' + b + ')'
        },
        drawPic() {
            const canvas = document.getElementById('s-canvas')
            const ctx = canvas.getContext('2d')
            ctx.textBaseline = 'bottom'
            // 绘制背景
            ctx.fillStyle = this.fixedBgColor ? this.fixedBgColor : this.randomColor(this.backgroundColorMin, this.backgroundColorMax)
            ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
            // 绘制文字
            for (let i = 0; i < this.identifyCode.length; i++) {
                this.drawText(ctx, this.identifyCode[i], i)
            }
            this.isDrawLine && this.drawLine(ctx)
            this.isDrawDot && this.drawDot(ctx)
        },
        drawText(ctx, txt, i) {
            ctx.fillStyle = this.fixedFontColr ? this.fixedFontColr : this.randomColor(this.colorMin, this.colorMax)
            ctx.font = (this.fixedFontSize ? this.fixedFontSize : this.randomNum(this.fontSizeMin, this.fontSizeMax)) + 'px SimHei'
            const x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
            const y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
            var deg = this.randomNum(-45, 45)
            // 修改坐标原点和旋转角度
            ctx.translate(x, y)
            ctx.rotate(deg * Math.PI / 180)
            ctx.fillText(txt, 0, 0)
            // 恢复坐标原点和旋转角度
            ctx.rotate(-deg * Math.PI / 180)
            ctx.translate(-x, -y)
        },
        drawLine(ctx) {
            // 绘制干扰线
            for (let i = 0; i < 8; i++) {
                ctx.strokeStyle = this.fixedLineColor ? this.fixedLineColor : this.randomColor(this.lineColorMin, this.lineColorMax)
                ctx.beginPath()
                ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                ctx.stroke()
            }
        },
        drawDot(ctx) {
            // 绘制干扰点
            for (let i = 0; i < 100; i++) {
                ctx.fillStyle = this.fixedDotColor ? this.fixedDotColor : this.randomColor(0, 255)
                ctx.beginPath()
                ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
                ctx.fill()
            }
        }
    }
}
</script>
